Reductive amination of nitriles in the presence of a secondary amine is a known process for preparing tertiary amines from nitriles. These reductions are generally run at high temperatures and pressures, and often result in poor selectivity, low conversions, or high secondary amine loading. The preparation of tertiary dimethylamines by the reductive amination of aliphatic nitriles with dimethylamine using heterogeneous catalysts has been explored. These reactions generally use liquid (anhydrous) dimethylamine and are performed at high temperatures (at or above 120° C.) and high pressures (80-200 bar or 8-20 MPa). The catalysts for these reductions are usually either palladium on a support or Raney nickel. In the latter case an improvement of the reaction was observed with inclusion of a catalytic amount of a hydroxide base, either in the catalyst preparation or in the reaction mixture itself. The use of high pressures for these hydrogenations requires expensive pressure-rated vessels and expensive and dangerous high pressure compressed hydrogen. The use of high temperature in these reactions can afford increased color (amines tend to discolor at high temperature) and reduced reaction selectivity due to side reactions of the starting materials or products. For example, substrates such as 3-hydroxypropionitrile or 3-dimethylaminopropionitrile may be prone to elimination reactions to afford acrylonitrile at elevated temperatures, which would lead to reduced yields of the desired products and contamination with side products from the acrylonitrile, necessitating significant product purification.